Production of colored photographic



Reissuecl May 11, 1943 Bela Gaspar, Hollywood, cum, assignm- Incorporated, a corporation of Chromogen, Nevada No Drawing. Original No. 2,270,118, dated January 13, 1942, Serial No. 179,591, December 13, 1937. Application. for reissue August 29, 1942,

Serial No. 456,695. In Great Britain Decembe 53 Claims. (01. 95-0) In my earlier patents a process has been described for the production of dyestuff images from diffusely dyed silver images. Thus, for example, according to my U. 8. Letters Patent 2,020,775, dated November 12, 1935', the production of such dyestuii images is performed by treating the difl'usely dyed silver image with solutions which destroy the dye locally in the presence of the metal deposit of the photographic image. At the same time the silver is partially or totally converted into a silver compound. Individual cases in which the destruction of the dye can be accelerated by the addition of certain substances have been described in my U. S. Patent No. 2,020,775.

It has been found that the eflectiveness of the dye destroying solutions described in my '0. 8. Patent No. 2,020,775 and of the other dye destroying baths which were found to be applicable in the process, can be accelerated by a great number of substances other than those heretofore known. -A.large number-of the new additions yield treating solutions which work in a much more effective manner, e. g. in a much shorter time or in far smaller concentration, than the products previously proposed as accelerators.

In view of the great eil'ectiveness oi the additions much smaller amounts of these accelerating substances are suflicienta In many cases the presence of the accelerating compounds in the ratio of 111011.000 is suihcient to multiply ea 2 oxy-3 -aminophenazine of the following formula:

quinoxaline of the following formula:

Akt. Ges.) may be activated by the addition of diphenyl-quinoxaline of the following formula or similar compounds of the general formula or which the formula I Example 1 A' 1% aqueous solution of hydrochloric acid which alone will not work satisfactorily on alayer diffusely colored by Diamine Fast Pink G (a dyestuff furnished by the I. G. Farbenindustrie 0.002% 2,3-diamino-phenazine. I

g Example 2 The action of a 2 $5 aqueous solution of hydrobromic acid on the dyestufl Heliotrope B (Schultz Farbstoiftabellen, 1931, 7th edition, vol. 1, N0.

494Fmay be considerably accelerated by the addition of 0.002% of diamino-phenazine. Even the addition of 7 parts of diamino-phenazine to one million parts of a hydrobromic acid solution of 1.66% strength has a distinct accelerating effect on the local destruction of I-Ieliotrope 13.

Example 3 For the production of multicolor images a multi-layer material may be used having difierent dyestufls incorporated in layers in which different color selection pictures are recorded. The dyestuifs may be for example Dlamine Pure Blue FF (Schultz loc. cit. No. 510)-, 'Benzo-Light-Yellow 4 GL extra (Schultz loc. cit. No. 308) and Sirius Ruby B (furnished by the I. G. Farben- A-Pontaininie Sky Blue 6 industrie Akt. Ges.). Thedye-destroying solution consists of 4% aqueous solution of hydrobromic acid which has been activated by the addition of 0.002% of diamino-phenazine.

Example 4 A solution containing 70' g. thiocarbamide, 30

g. hydroquinone, 50 g. chrome alum, 5 com, sulphuric acid (d=1.85) per liter, with the addition of 0.2 g. 2,3-diamino-phenazine is used for treating exposed and developed silver halide layers containing the dyestuflobtained from diazotised ortho-anisidlne and resolcinol. A dyestuff image is obtained after 7 minutes treating.

Example 5 A solution containing 74 g. potassium bromide 'and 17 ccm. sulphuric acid (d=-1.84) per liter is saturated with 2,3-diphenyl-quinox'aline and then contains less than 0.01 g. per liter of this suhstance. The solution, acts on silver images dyed with the dyestufl obtained from diazotlsed 4-amino-l -benzoylamin 3 methoxy-G-methylhenzol and p-naphthol within 25 minutes or on the dyestufi obtained from diazotised o-anisidine and resorcinol within 30 minutes or on the dyestuif obtained from diazotised p-nitraniline and p-naphthol within 60 minutes.

With this dyestufl and with the same treating bath the same result is obtained if, instead of the 2,3-diphenyl-quinoxaline, the 2,3 dimethylquinoxaline, the 2-oxy-3-methylquinoxaline or ordinary quinoxaline are used, 2 g. of each accelerator being used perliter. The dyestuffs chosen for the tests are in most casesinsoluble azo dyestuifs which in themselves are diflicult to bleach out. In using dyestuffs of this sort, the

differences are naturally more evident than if dyestuffs are employed which are bleached out in a shorter time in a dyestuil. destroying bath without admixture. In. using insolubie dyestuffs which are difilcultly bleached. the difference is so great that, for instance, the thio-carbamide bath mentioned in Example 4 which, with an admixture of, for instance, 2,3-diamino-phenazine destroys the dyestufi's locally after '7 or 8 minutes of treatment, shows practically no useful effect if the accelerating substance is omitted, even if the time of treatment is doubled.

Mention should, however, be made oi the fact that the application of the admixtures has certain advantages even in the case of easily soluble and easily bleaching dyestuffs, .such as a short ening of the time of treatmentand therebya decrease of the detrimental eifect on the layer. The results of'a large number of compounds which have been tested and found to be useful accelerators are given in the following list which shows the accelerating-effect obtained by the addition of various substances to a number of treating baths used in producing dyestufi images from silver images dyed by six different dyestuiis. These dyestuffs are:

carbocyanine-iodide.

. Accelerating eflect on Dyestui! Cam-m hydrochloric acid 11% used 5 1.. Benzhydrnl A, B,("- 2..." Alphabenzil-dioxime.--. A,B G 3.... zophenone-anil......

4 Cyanamide 0 5....- Dgacctyl-monomcthox- A, B, 0

rue. 6 Dlacetyl-monoxiinc...... A, B 7 Dibenzylamine A, B

10 s---.. Diphenyl-piperazine...-. A, B 0... Diphcnyl-thiocarbazonc. A B 10.... Hydrobenzamide A, C 11.... Methylcno-ainmdaccto- A,l3

nitrilc. 12.... Quinizarin A,B 13.... Quinaphthalone A, B 14.... 2,2',4,4'-tetrarnino-5, 5- A, B

' dimethyl-diphenylmethane. 15.... Ti-tra-ethyl-p-diamino- A, B

bcnzoplienone. 10.... Tetra-ethyl-p-pdia- A, B

mino-diphenyl-mcthane. 17.... Bcnzothio-diazol.. A, B, C 18. 2, 3 dimcthyl-quinoxa-- no. 19.... 2, 3 diamino-phcnazinc.. A, B, I. I! 2-oxy-3-amino-phenazino. AI 13 C 21.... N, 1. '-di (puraamino- A,

phenyl) N, N'-dimethyl-ethylcne-diamine. 1

Methyl violet B A, B, C 23.... Auramine A, B 21 Diacetylp.- phenylene- B,

diamine.

25.... S-diphenylcthylenc-dia- A, B

mine.

26.... 2, 4 -dianiinodiplicnyl- +++-i- A, B

amine.

27..-. Quinizarln sulphonic A, B

Sodium indigo sulphon- A, B

ate.

20.... 1, 2, 4-triaminobenzcnc- B trihydrochloride.

0 30.... Tetrametliyl diamino- A, B, C

benzhydrol. 31.... Tetramethyl-pdiamino- A, B, C

bcnzophenone. 32.... Tetramethyl-p-pheny- A, B, C lene-diamine hydrochloride. 40 33.... Tctramcthyl-odiamino- A, B

diplienyl methane. 34.-.. N-methyl-quinolone.. Hydrobromic acid 5% A, B

35..-. Nmethyl-quinolone.. Hydrochioiiiacid 11% A, B 30.-" Acetone phcnylhdra- A, B

zone.

37.--. Acetone-ammo... C 38.- Acridone A, ll 39. fi-amino-purinc sulphate. A B 40.-.. Ammo-pyrine A, B, C 41.. Allantmn A, C 42.... Anthraguinone-betasul- A, B

phonic acid.

, 43.. Benzalmethylam1ne...-- A, C

44.-.. Diacetyl o phcnylen- A, B

diamuie. 4. Benzthiazyl hydrazine-.. A, ll 46-. 2,ch}or-4,li-diam1no-bcn- A, B

to 47.." Sym.diph cnyl-carbazide A, B

5 48.- Anthraqumone A, B, C

. 2,3-di phenyl-quinoxaline A, B 50.... l,am no-ahthraquinone.. A, B 5L-.- 2,amino-anthraquinone.. A, B

A B 1,13, 0 54 A,B 55.--- Al zarlne-red-Agfa A, B 56..-. D1 hydro 2 hydroxy- A, I;

. quinoxaline. 1 57---- Fuchsine. 'A 58.-.. Anthraqu nono bcta- Sodium hyposulphite sulplionic acid. 20 50.... Tetramethyl p diam- Accelerating eflect on D mo-bcnzophenonc. hydrochloric acid 11% 60.-.. Quinizarino sulphonic Sodium chloride 20% E acid. plus hydrochloricacid 61.... .do Magnesium chloride F Plus hydrochloric ac 62.--. Dimethylamlnostyryl Hydrochloric acid 11% A, B 10 dunethyl thlazol N 63 6 mettllliyliodide.d 4

..-- ,me oxypseu ocyani- B ne N-ethyl-iodide. N-ethyl-fi,methoxy-thio- B carbooyanine-iodide. 65.--. N ethyl benzthioazol- A, B

. different chemical groups.

Accelerating eflect on Dyestuil No Catalyst hydrochloric acid 11% used 66.... Quinonc A, B, C 67.--. Benzalanilinc 1 68.. lieeamethylenctetrs- 5,13

in no.

.60.... Benzalazine..... A,B 70. -Toluol-sulphinic acid. 71.. cnzenoJ-sulphonic 3- C sulphlnicacid.

72.. Naphthalene-l-sulphou- +v C- a lc 4-sulphinic acid.

73.. (3l-nitrostyryl-quinolm- A, B

ium-N-ethyl-ethylsulphonate.

.74.... (3)-nitrostyryl-bcnzthi- A, B

' azol-ethyl-sulphonatv. Y 75;... (3)-sulph n-styryl-pscu- A, B dothiohydantoine.

76.. Styryl quinolinium- A, B

othyl-sulphonatc.

77.... (4) dimctllylaminn A, B

styryl-rhodauine 78.... Bisfl-dimnthylammo-2- A, B a

' pin-((11 phcnyl) disul- A, B

p n c. a

The foregoing list of accelerating compounds embodies the results obtained with catalysts belonging to various classes of compounds. It includes, for example, reducing substances of the general type disclosed in my earlier Patent No. 2,020,775, dated November 12, 1935. In addition, the list includes compounds of the class of reducible substances, the accelerating eflect of which was heretofore unknown. The claims of the present application are directed to reducible substances although the general listing of compounds has been set forth to indicate the comparative activity of the various compounds. In the present application, no claim is made to the reducing substances disclosed and claimed in my above-mentioned Patent No. 2,020,775.

The quantity of the added catalyst was 0.2% in the experiments Nos. 1 to 57 and 60 to 69 of the list, whereas 0.8% wasused in No. 58 and 0.5% in No. 59. In Nos. 70 to 72 1% of the addition was used. In Nos. 73 to 77 the quantity of the addition was again 0.05%. In many cases far smaller quantities or the catalyst may be used for practical purposes.

' group oi catalysts. Also the compounds coni a ring system (No. 39) or in an open chain. See Nos. 2, 3, 5, 6,11, 36, 37, 43. Compounds of the quinone-imide type or indophenols belong to this taining the -CEN group shown in many cases an acceleratingefiect. A large class of accelerators is found in the classof sensitizing or desensitizing dyestuffs. See for example Nos. 62, 63, 64, 65, 73 to 7-7. The capacity or accele'rating appears to be in no direct proportion to the sensitizing properties but on the contrary to be based mainly on the fact that these dyestuffs usually belong to one of the above-mentioned groups of accelerating substances. noted that organic sulpho-compounds containing As can be seen the new catalysts belong. to

They are in most cases organic substances which can be easily hydrated or dehydrated. Compounds, reduction-products or oxidation-products of which are. capable of forming a reversible redoxsystem, are especially suitable. See, for example. Nos. 26, 33, 57. Furthermore, organic bases which can be easily oxidized may be used. See Nos. 29, 32, 44. In many cases the bases themselves are not especially effective but can be rendered more suitable by the formation of oxidation products by auto-oxidation. The oxidation products of such bases are very suitable catalysts.

cases the eii'ective compounds are characterized either in by the presence of the group the I Heterocylic bases can also be used. See Nos. 17, 8. In many cases the compounds which are found to be suitable catalysts are characte In other tion to the dyes, catalysts ortreating solutions used in the examples.

What I claim is:

1. In the process of producing a photographic dyestufi image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a metal image, the step of treating said metal image with a solution containing a substance capable of selectively destroying said azo-dye by reduction in the presence of said metal image,

said solution also comprising a smallamount of a reducible organic accelerating substance selected from the group of those reducible substances, the reduction products of which are reoxidizable during the treatment of said metal image with said solution to the original reducible substance, the composition of said solution being such that the reduction products of said reducible substance are reoxidizable during the treatment of said metal image and said solution being initially substantially free of reducing substances capable of being converted into said reducible substance by oxidation.

2.'In a process of producing a, photographic dyestuil image in a photographic emulsion uniformly dyed by an azo-dye andalso comprising a silver image, the step of treating said silver image with a solution comprising a substance which is capable of forming complex silver compounds and which acts to selectively destroy said azo-dye by reduction in the presence of said silvar image, said solution-also comprising a small amount of a reducible organic accelerating substance selected from the group of those reducible substances, the reduction products of which are ireoxidizable during the treatment of said silver image with said solution to the original reducible substance, said solution being such that the reduction products of said reducible substance are reoxidizable during the treatment of said silver image and said solution being initially substantially free of reducing substances capable of being converted into said reducible organic substance by oxidation.

contain ng an. a ent w ich. is IlfI'ldEStlUCtiVf-l with respect to the dyestufi. but reacts with the said metal to oxidize it and substantially simultaneously to form a reducing substance which It may be destroys said azo-dye at the points of the metal image, said solution also comprising a reducible organic accelerating substance selected from the group of those reduciblesubstances, the reduction products of which are reoxidizabl during the treatment of the metal image with said solution to the original reduciblesubstance, the com position of said solution being such that the reduction products of said reducible substance are reoxidizable during treatment of the metal image and said solution being initially substantially free V of reducing substances capable of. being converted into said reducible substance by oxidation.

4; In a process of producing a photographic dyestufl image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a silver image which comprises the step'of treating the said silver image with a solution containing an agent which is non-destructive with respect to the dyestuif, but reacts with the said silver image to oxidize it and substantially simultaneously to form areducing substance which destroys said azo-dye at the points of the silver image, said solution also comprising a reducible organic accelerating substance selected from the group of those reducible substances, the reduction products of which are'reoxidizable duri the treatment of the silver image with said solution to the original reducible substance, the composition of said solution being such that the reduction products of said reducible substanceare reoxidizable during treatment of the silver image and said solution being initially substantially free of, reducing substances capable of being converted into said reducible substance by oxidation. v

5. A treating bath for producing a photographic dyestufi' image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a metal image, comprising a solution of a substance capable of selectively destroying said azo-dye by reduction in the presence of said metal image, said solution also comprising a graphic dyestulf image in a "photographic emulsion uniformly dyed by an azo-dye and also comprising a silver image, comprising a solution of an agent which is non-destructive with respect to the dyestufl, but reacts with the said,

silver image to oxidize it and substantially simultaneously to form a. reducing substance which destroys said azo-dye at the points of the silver-- image, said solution also comprising a reducible organic accelerating substance which is reducible dyestufl image in a photographic emulsion uniformly'dyed by an, azo dye and also comprising a silver image, the step of treating said silver image with a solution containing a substance capable of selectively destroying said azo-dye by reduction in the presence of said silver image, said solution also comprising a small amount of a reducible organic accelerating substance selected from the group consisting of unsubstituted or substituted compounds on the following gensmall amount of a reducible organic accelerating substance selected from the group of those re ducible substances, the reduction products of which are reoxidizable during the treatment of said metal image with said solution to the original reducible substance, the composition of said solution being such that the reduction products of said reducible substance are reoxidizable during the treatment of said metal imageand said J solution being initially substantially free of reducing substances capable of being converted into said reducible substance by oxidation.

6. A treating bath for producing, a photographic dyestuil. image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a silver image, comprising a compound capable of forming complex silver compounds and which acts to selectively destroy said azodye by reduction in the presence of said silver image and also a small amount of a reducible organic accelerating substance which is reducible and the reduction products of which are reoxidizable during the production of said'image to the original reducible substance, the composition of said bath being such that the reduction products of said reducible substance are reoxidizable during the treatment of said photographic emulsion and said bath being initially substantially free of reducing substances capable of being converted into said reducible substance by oxidation.

'1. A treating bath for producing a photoeral formula in which X and Y represent a group, selected from the group consisting of N and 0:0, and

in which a and b represent a residue selected from the group consisting of hydrogen, methyl, phenyl and four-membered carbon-chains forming a condensed ring system, the substituents being selected from the group of substituents conslsting of amino-groups, oxy-groups, alkylgroups, aryl groups and sulphonic groups.

9. A treating bath for producing a photographic dyestufl image in a photographic emul-- sion uniformly dyed by an azo-dye and also comprising a silver image, comprising a solution of a substance capable of selectively destroying said azo-dye by reduction in the presence of said silver image, said solution also comprising a small amount of a reducible organic accelerating substance which is reducibl during the production of said dyestufl? image selected from the group consisting of unsubstituted or substituted compounds of the following general formula groups, alkyl-group's, aryl-groups and sulphonic 10. In the process of producing a photographic dyestuil image in a photographic emulsion uniion nly dyed by an azo-dye and also comprising a silver image, the step or treating said silver image with a solution containing a substance capable of selectively" destroying said aao-dye by reduction in the presence or said silver image, said solution also comprising a small amount of a reducible phenazine compound capable of being reduced during the treatment of said silver image.

11. A treating bath for producing a. photographic dyestuil! image in a photographic emulsion uniiormlydyed by an a'zo-dye and also comprising a silver image, comprising a substance capable of selectively destroying said azodye by reduction in the presence of said silver image, said bath also comprising a small amount 0! a phenazine compound which is reducible during the production of said dyestufl image.

12. In a process of producing a photographic dyestuilf image in a photographic emulsion uni- !ormly dyed by an azo-dye and also comprising a metal image, the step of treating the said metal image with a solution containing an agent which.

is non-destructive with respect to the dyestufi, but reacts with the said metal to oxidiz it and substantially simultaneously to, form a reducing substance which destroys said azo-dy'e at the points of the metal image and further contain- 'ing a small amount of a phenazine compound which is reducible during the production of said image.

13. A treating bath for producing a photographic dyestuilf image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a silver image, comprising a substance :2 which is non-destructive with respect to the dye stufl, but reacts with the silver to oxdize it and complex silver compounds and which acts to selectively destroy said azo-dye'by reduction in the presence or said silver image and a small amount of a phenaz'ine compound which is reducible during the production of said dvestuii images Y I 15. A treating bath for producing a photographic dyestufl' image in a photographic emulcases sion uniformly dyed by an azo-dye and also comducible during the formation of said dyestufl image.

17. A treating bath for producing a photographic dyestufi image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a silver imageQcomprising a substance capable of forming complex silver compounds and which acts to selectively destroy said azodye by reduction in the presence oi said silver image and a small amount of a quinoxaline compound which is reducible during the production of said dyestufl image. I

18. In a process for producing a photographic dyestuil' image in a photographic emulsion uniiormly dyed by an azo-dye and also comprising a metal image, the step of treating the said photographic emulsion with a solution containing an agent which is non-destructive with respect to the dyestufi, but reacts with the said metal to oxidize it and substantially simultaneously to form a reducing substance which destroys said azo.dye at the points of the metal imageland further containing a small amount 1 of a quinoxaline compound which is reducible during the production 01 said dyestuii' image.

v19. A treating bath' for producing a photo.-

graphiedyestufiimage in a photographic emulprising a silver image comprising a substance capable of selectively destroying said azo-dyeby reduction in the presence of said silver image,

"said bath also comprising a small amount of a qulnoxaline compound which is reducible during the production of said dyestuif image.

20. A treating bath 'for producing a photographic dyestuif image in a photographic emulsion uniformly dyed by an azo-dye and also com-- prising a silver image comprising thiocarbamide and a small amount of a reducible organic acceler'ating substance which is reducible and the reduction products of which are reoxidizable dursion uniformly dyed'by an azo-dye and also com-Y prising a silver image, comprising'a submmce' capable of forming complex silver compounds and which acts to selectively destroy said azo- V dye by reduction in the presence oi! said silver .image and a small amount 01 a phenazlne coming the production of said dyestuii image to the original reducible substance, the composition of 'said treating bath being such that the reduction products are reoxidizable during the pro- '21. In a process of producing a photographic dyestufl image in a photographic emulsion uniiormly dyed by an azo-dye and also comprising a silver image, the step of treating the said silver image with a solution of thiocarbamide and a small amount oi a reducible organic accelerating substance selected from the'group of those reducible substances, the reduction products of which are reoxidizable during the treatment of said silver image with said solution to the original reducible substance, the composition of said solution being such that the reduction products of said reducible substances are redyestuf! image'in a photographic emulsion unicomplex silver compounds and which acts to selectively destroy said ago-dye by reduction in the presence of said silver image and a small amount of a quinoxaline compound which is oxidizable during the treatment of the silver image and said solution being initially substantially free of'reducing substances capable of being converted into said reducible substance by oxidation. r

22. A treating bath for producing a photographic dyestuii image in a photographic emulsion uniformly dyed by an azo-dye and also comprislng'a silver image, comprising a solution of thiocarbamide and a small amount of a reducible organic accelerating substance selected from, the group of those reducible substances, the reduc-'.

.tion products of which are reoxidizable during composition of said solution being such that the. reduction products of said reducible substance.

are reoxidizable during the treatment of said silver image and said solution being initially substantially free of reducing substances capable of being converted into said reducible substance by 7 oxidation.

23. In a process for producing a photographic dyestufl image in a photographic emulsion uniiormly dyed by an azo-dye and also comprising a silver image, the step of treating said silver image with a solution comprising thiocarbamide and a small amount of a phenazine compound which is reducible during the production of said dyestuil image.

24. A treating bath for producing a photographic dyestufl' image in a photographic emul sion uniformly dyed by an azo-dye and also comprising a silver image, comprising a solution of thiocarbamide and a small amount of a phenazine compound which is reducible during the production of said dyestufl image.

25. In a process iorproducinga photographic dyestufl. image in a photographic emulsion unii'ormiy dyed by an azo-dye and also comprising asilver image, the step of treating the said emulsion with a solution of hydrohalic acid and a small amount of a reducibl organic accelerating substance selected from the group of those reducible substances, the reduction productsl'of which are reoxidizable during the treatment of said silver image with said solution to the original reducible substance, the composition of said solution being such that the reduction products of said reducible substance are reoxidizable during the treatment of said silver image and said solution being initially substantially free-ofreducing substances capable of being converted into said reducible substance by oxidation.

26. A treating bath for producing a photographic dyestufl. image in a photographic einulsion uniformly dyed by an azo-dye and also comprising a silver image comprising hydrohalic acid and a small amount of a reducible organic accelerating substance which is reducible and the re duction products of which are reoxidizable during the production of said dyestuff image to the original reducible substance, the composition of said treating bath being such that'the reduction products are reoxidizable during the production of said dyestufi' image and said treating bath being initially substantially free of reducing substances capable of being converted into said reducible substance by oxidation.

27. In a process of producing vva photographic dyestufl image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a silver image, the step of treating said photographic emulsion witha solution containing hydrohalic acid and a small amount of a reducible organic accelerating substance selected from the group consisting of unsubstituted and substituted compounds of the following general formula in which X and Y represent a-group selected from the group consisting of N and and in which a and b represent a residue selected from eases condensed ring system, the substituents being selected from the group of substituents consisting of amino-, oxy-, alkyl-, aryland sulphonic groups.

'28. A treating bath for producing a' photographic dyestufl image in a photographic emu1- sion uniformly dyed by an azo-dye and also comprising a silver image comprising hydrohalicacid and a small amount of a reducible organic accelcrating substance which is reducible during the production of said dyestufi image selected from the group consisting of unsubstituted or substituted compounds of the following general formula in which X and Y represent a group, selected from the group, consisting of N and 0:0, and V in which a and b represent a residue selected from the group consisting of hydrogen, methyl,

phenyl, and iour-membered carbon-chains formand a small amount of a phenazine compound which is reducible during the production of said dyestufl image.

30. A treating bath for producing a photographic dyestuff image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a silver image, comprising hydrohalic acid and a small amount of a phenazine compound which'is reducible during the production of said dyestufl image.

31. A process for producing a photographic 'dyestuif image in a photographic emulsion uniformly dyed by' an azo-dye and also comprising a silver image, which comprises treating; said' photographic emulsion with a solution comprising hydrohalic acid and a small amount of a quinoxaline compound which is reducible during the production of said dyestui! image.

32. A treating bath for producing a photographic dyestufl image in a photographic emulsion uniformly dyed with an azo-dye and also comprising a silver image, comprising hydrohalic acid and a small amount of a quinoxaline compound which is reducible during the production I of the said 'dyestufl image.

33. In a process for producing 'a' photographic dyestufl image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a silver image, the step of treating-the said silver image with a solution comprising hydrochloric acid and asmall amount of a reducible organic accelerating substance selected from the group of those reducible substances, the reduction prodnets of which are reoxidizable during'the treatment of said silver image with said solution to the original reducible substance, the composition of said solution being such that-the reduction products. of said reducible substance are reoxidizable during the treatment of said silver image and said solution beinginitially substantially free of reducing substances capable of being converted into said reducible substance by oxidation.

aasos 34. A treating bath for producing a photographic dyestuilf image in a photographic emulsion uniformly dyed by an azo-dye and also comprising a silver image, comprising hydrochloric acid and a small amount or a reducible organic accelerating substance which is reducible and the reduction products of which are reoxidizable during the production of said dyestufi' image to the original reducible substance, the

composition of said treating bath being such that the producti of aid dyestufl ima the reduction products are reoxidizable during the production ofsaid dyestuil? image and said treating bath being initially substantially free of reducing substances capable of being converted into said reducible substance by oxidation.

35. In a process of producing a photographic dyestuii image in a photographic emulsion unitormly dyed by an azo-dye and also comprising a silver image, the step of treating said photo graphic emulsion with a solution containing hydrochloric acid and a small amount 0! a reducible organic accelerating substance selected from the group consisting of unsubstituted and substituted compounds of the following general formula in which X and Y represent a group selectedfrom the group consisting of N and C =O and in which a and I) represent a residue selected from the group consisting of hydrogen, methyL'phenyl, and iour-membered carbon-chains forming a condensed ring system, the substituents being selected from the group.of substituents consisting of amino-, oxy-,- alkyl-, aryland sulphonic groups. 36.'A treating bath for producing a photographic dyestufl' image ina photographic emulsion uniformly dyed'by an azo-dye and also comprising a silver image, comprising hydrochloric acid and a small amount of a reducible organic accelerating substance which is reducible during the production of said dyestufi image selected from the group consisting of unsubstituted or substituted compounds of the following general formula v40. A treating'bath for producing a photographic dyestufi imagein a photographic emulsion uniformly dyed with an azo-dye and also comprising a silver image, comprising hydrochloric acid and a small amount of a quinoxaline compound which is reducible during the production of the said dyestufi image. I

41. In a process of producing a dyestufi image in a photographic emulsion comprising a metal image and an azo dyestuif, the step of treating said azo dyestufi in the presence of said metal image with an agent which in the presence of said metal image is capable of selectively destroying said azo dyestufi by reduction, said treatment being carried out in the presence of a quantity of a reducible organic accelerating. substance suflicient to accelerate the selective destruction of said azo dyestufi, the said accelerating substance being selected from the group of those reducible substances, the reduction products of which are reoxidizable during said treatment of said azo dyestuff in,the presence of said in'which X and Y represent a group selected from the group consisting of N and 0:0 and in which a and b represent a residue selected from the group consisting of hydrogen, methyl, phenyl,

image with a solution comprising hydrochloric acid and a small amount or a phenazine compound which is reducible during the production of said dyestufl image.

. 1 7 38. A treating bath for producing 'a photographic dyes'tuil' image in a photographic emulsion uniformly dyed by an-azo-dye and also comprising a silver image, comprising hydrochloric acid and a small amount or a phenazine commetal image to the original reducible substance, said treatment with said organic reducible accelerating substance being initiated in the absence of reducing substances capable of being converted into said reducible substances b oxidation and the conditions of said treatment being such that the reduction products of said reducible substance are reoxidizable' during said treatment of said azo dyestufi.

42. In a process of producing a dyestuff image in a photographic emulsion comprising a silver image and an azo dyestufi, the step of treating said am dyestuil in the presence of said silver image with an agent which in the presence of said silver image is capable of selectively destroying said azo 'dyestufl by reduction, said treatment being carriedout in the presence of a quantity of a reducible organic accelerating substance suflicient to accelerate the selective destruction of said azo dyestufl, the said accelerating substance being selected from the group of those reducible substances, the reduction products of which are reoxidizable during said treatmenttof said azo dyestufi in the presence of said silver image to theoriginal reducible substance, said treatment with said organic reducible accelerating substance being initiated in the absence of reducing substances capable of being converted into said reducible substances by oxidation and the conditions of said treatment being such that the re- .duction products of said reducible substance are reoxidizable during said treatment of said azo dyestufi.

43. In a process of producing a dyestuii image in a photographic emulsion comprising'a metal image and an azo dyestuflf, the step of treating said azo dyestufi in the presence of said metal image with an agent whichin the presence of said metal image is non-destructive with. respect to the dyestuii', but reacts with the said metal to oxidize it and substantially simultaneously to form a reducing substance which destroys said pound which is reducible during the production" azo dyestufi at the points of the metal image. said treatment being carried out in the presence of a quantity oi'a reducible organic accelerating substance suflicient to accelerate the selective destruction of said azo dyestufl', the said accelerating substance being selected from ,the group of those reducible substances, the reduction prodnets of which are reoxidizable during said treatment of said azo dyestufl in the presence of said metal image to the original reducible substance, said treatment being initiated with said organic reducible accelerating substance in the absence oi'reducing substances capable of being converted into said reducible substances by oxidation and the conditions of said treatment being such that the reduction products of said reducible substance are reoxidizable during said treatment of I said azo dyestufi. I

44. In a process of producing a dyestufl image in a photographic emulsion comprising a silver image and anazo dyestufl, the step of treating said azo dyestufi in the presence of said"silverimage with an agent which in the presence of said silver image is non-destructive with respect to the dyestufl, but reacts with the said'silver to oxidize it and substantially simultaneously to form a reducing substance which destroys said treatment being carried out in the re ence oi-a ill " azo dyestufl at the points 01' the silver-imagasaid destruction of said azo dyestufl, the said accelcrating substance being selected from the group of those reducible substances, the reduction products 0! which are reoxidizable during said treatment of said azo dyestufl in the presence 01' said silver image to the original reducible substance, said treatment with said organic reducible accelerating substance being initiated in the absence of reducing substances capable of being converted into said reducible substances by oxidation and the conditions of said-treatment being such that the reduction products of said reducible substance are reoxidiz'able during said treatment of said azo dyestuii;

47. In a process of producing a dyestuflf image in a photographic emulsion comprising a silver image and an az o 'dyestufi, the step of treating said azo dyestufl in the presence of said silver ucts of which are reoxidizable during said treatment of said azo dyestuflf in the presence'of said silver'image to the original reducible substance,

, said treatment with said organic reducible accel ing substance being selected from the group of Q those reducible substances, the reduction products of which are reoxidizable during said treatmentor said azo dyestufl in the presence of said silver imageto the original reducible substance, said treatment being initiated with said organic reducible accelerating substance in the absence of reducing substances capable of being converted into said reducible substances by oxidation and the conditions or said treatment being such that the reduction products of said reducible substance are reoxidizable during said treatment of-said azo dyestufi.

45. In a process of producing a dyestufi image in a photographic emulsion comprising a metal image and an {azo dyestufi, the step of treating said azo dyestufi in the presence of said metal image with a, solution comprising hydrohalic acid, said treatment being carried out in the presence of a quantity of a reducible organic accelerating substance suflicient to accelerate the selective destruction of said azo dyes'tufl, the said accelerating substance being selected from the group of those reducible substances, the reduction products of which are reoxidizable during said treatment of said azo dyestuff in the presence of said metal image to the original reducible substance, said treatment with said organic reducible accelcrating substance being initiated in the absence of reducing substances capable of being converted into said reducible substances by oxidation and the conditions or said treatment being such that the reduction products 01' said reducible substance are reoxidizable during said treatment of era ting substance being initiated in the absence of reducing substances capable of being converted into said reducible substances by oxidation and the conditions of said treatment being such that the reduction products of said reducible substance are reoxidizable during said treatment 01 said azo dyestufi.

48. In a process of producing a dyestui! image I substance s'aid treatment with said organic reducible accelerating substance being-initiated in the absence of reducing substances capable of.

. being converted into said reducible substances by oxidation and the conditions oi said treatment being such that the reduction products of said reducible substance are reoxidizable during said treatment of said azo dyestufl.

49. In a process of producing a dyestufi image in a'photographic emulsion comprising a metal image and an azo dyestuii', the step of treating said azo d'yestufl in the presence ofsaid metal said azo dyestufl by reduction, said treatment being carried out in the presence of a small amount of a reducible'organic accelerating subsaid treatment being carried out in the presence of a quantity of a' reducible organic accelerating substance suflicient to accelerate the selective stance selected from the group consisting of unsubstituted or substituted compounds of the following general formula in which X and Y' represent a constituent selected from the group consisting of N and :0, and in which a and b represent a residue selected from the group consisting of hydrogen, methyl, phenyl, and four-membered carbonchalns forming a condensed ring system, the substituents being selected from the group of substituents consisting of amino-groups, wry-groups; alkyl-groups, aryl-groups and sulphonic groups.

50. In a process of producing a dyestufl image in a photographic emulsion comprising a silver image and an azo dyestufl, the step of treating said azo dyestutl' in-the presence of said silver image with an agent which in the presence of said silver image is capable of selectively destroying said azo dyestufl by reduction. said treatment being carried out in the presence of a small amount of a reducible organic accelerating substance selected from the group consisting of unsubstituted or substituted compounds 01' the following general formula phenyl, and iour-membered carbon-chains form ing a condensed ring system, the substituents being selected from the group of substituents consisting of amino-groups, oxy-groups, a-Ikylgroups, aryi-groups and sulphonic groups.

52. In' a process of producing a dyestufi image in a photographic emulsion comprising a silver imrge and an azo dyestuil', the step of treating said azo dyestufl in the presence of said silver image" with a solution comprising hydrochloric acid, said treatment being carried out in the presence of a small amount of a reducible organic accelerating substance selected from the group pounds of the following general formula in which X and Y represent a constituent selected from the group consisting of N and C=O,

' and in which a and I) represent a residue selected in which X and Y represent a constituent selected from the group consisting of N and (i=0. and in which a' and b represent a residue selected from the group consisting of hydrogen, methyl, phenyl, and four-membered carbon-chains forming a condensed ring system, the substituents being selected from the group oi substituents consisting of amino-groups, oxy-groups, alkylpounds of the following general formula YI/ b in which X and Y represent a constituent selected from the group consisting of N and 0:0, and in which a and I: represent a residue selected from the group consistin of hydrogen, methyl,

from the group consisting of hydrogen, methyl, phenyl, and four-membered carbon-chains forming a condensed ring system, the substituents being. selected from the group of substituents consisting of amino-g'roups, oxy-groups, alkylgroups. aryl-groupsand sulphonic groups.

53. In a process of producing a dyestufi image in a photographic emulsion comprising a silver image and an vazo dyestuif, the step of treatin said am dyestufl in the presence of said silver image with a solution comprising thiocarbamide,

. said treatment being carried out in the presence of a small amount of a reducible organic'accel- .r erating substance selected from the group consisting of unsubstituted or substituted compounds of the following general formula condensed ring system, the substituents being selected from the group of substituents consisting of amino-groups, oxy-groups, alkyl-groups, arylgroups and sulphonic groups.

BELA GAsPAa 

